Grapevine plant named ‘Caminante Blanc’

ABSTRACT

A new and distinct variety of grapevine plant named ‘Caminante Blanc’, particularly selected for its high resistance to Pierce&#39;s disease, as well as quality of fruit and wines produced is disclosed.

Botanical classification: Vitis vinifera L.

Varietal denomination: The varietal denomination of the claimed variety of grapevine plant is ‘Caminante Blanc’.

BACKGROUND OF THE INVENTION

Pierce's disease (PD) is common across the southern United States from Virginia to northern California. It is also common across Mexico and Central America. The disease is caused by the bacterium Xylella fastidiosa, which is hosted by a very wide range of native and ornamental plants. The bacterium is spread by xylem feeding insects as vectors, primarily sharpshooters. PD is one of the few diseases that rapidly kills wine, table, and raisin grape cultivars of the cultivated grape, Vitis vinifera. Vector populations can be limited with insecticides, but these are difficult to use near their typically riparian native habitat or in the ornamental landscapes in which they flourish. Breeding for PD resistance has been active for over 70 years, but progress has been very slow due to a poor understanding of the germplasm and the typically multigenic nature of the resistance in most of the resistant grape species. The two most commonly grown PD resistant varieties, ‘Blanc du Bois’ and ‘Lenoir’ (‘Lenoir’ is also known as ‘Black Spanish’ or ‘Jacquet’), are F₁ hybrids between V. vinifera cultivars and resistant American grape species from the southern United States, and are therefore only about 50% of V. vinifera. ‘Blanc du Bois’ and ‘Lenoir’ produce wines with lower quality than V. vinifera wine grape varieties, and they are tolerant of, rather than resistant to, X. fastidiosa infection, which results in their potential to expand areas damaged by PD due to their ability to act as host plants for the bacteria and vectors.

Grapevine is an important and valuable crop. Accordingly, there is a need for new varieties of grapevine plant. In particular, there is a need for improved varieties of grapevine plant that produce high quality fruit for winemaking and are resistant to Pierce's disease.

SUMMARY OF THE INVENTION

In order to meet these needs, the present invention is directed to an improved variety of grapevine plant. In particular, the invention relates to a new and distinct variety of grapevine plant (Vitis vinifera L.), which has been denominated as ‘Caminante Blanc’. Grapevine plant variety ‘Caminante Blanc’ possesses very strong resistance to the bacterial causal agent of Pierce's disease (PD), and produces very high quality fruit and wines therefrom that are indistinguishable from the widely grown European wine grape cultivars. Other PD resistant cultivars are known, but their fruit and winemaking quality are poor in comparison to ‘Caminante Blanc’ and their resistance is much lower.

In particular, grapevine plant variety ‘Caminante Blanc’ is a white wine grape selection that is about 97% V. vinifera (including 62.5% ‘Cabernet Sauvignon’, 12.5% ‘Chardonnay’, and 12.5% ‘Carignane’) and is highly resistant to PD as shown in repeated greenhouse evaluations. In comparison, the two most commonly grown PD resistant varieties, ‘Blanc du Bois’ and ‘Lenoir’, are only about 50% of V. vinifera. ‘Caninante Blanc’ has been planted in field trials in Davis and in Ojai, Calif. ‘Caminante Blanc’ has small berries and small compact clusters. It blooms relatively late, ripens mid-season, and has medium productivity. Wines made from fruit of ‘Caminante Blanc’ grown in Davis, Calif. may be described as: ‘light straw-gold color’, ‘apple-melon’, ‘lychee’, ‘floral aromas’, ‘pineapple’, ‘green apple’, ‘juicy’, ‘harmonious’, and ‘well-balanced’.

Pedigree and Breeding History

The development of this new grapevine variety is in part a result of the discovery of a single dominant gene for resistance to Xylella fastidiosa, the bacterial causal agent of Pierce's disease (PD). The source of the PD resistance is a form of V. arizonica (‘b43-17’) that appears to have some candicans parentage and is from Monterrey, Mexico. ‘b43-17’ was crossed to the susceptible V. rupestris ‘A. de Serres’ to create the F8909 population, Neither ‘b43-17’ nor ‘A. de Serres’ are patented. The resistance from ‘b43-17’ was found to be inherited as a single dominant gene (locus), and this resistance gene, PdRl, was genetically mapped using the F8909 population by a grapevine breeding program. Tightly linked simple sequence repeat (SSR) markers were developed and were used in marker-assisted selection to exclude susceptible plants from evaluation in each round of selection. All the progeny with PdRl were tested for PD resistance and only those with strong resistance were considered for use as parents. Potential parents were also screened for fruit quality over generations and only those with good quality fruit and that appeared like V. vinifera were selected.

Line ‘F8909-08’ from the F8909 population was crossed to ‘P79-101’, a highly susceptible, advanced V. vinifera table grape selection from a grape breeding program. The resulting ‘F8909-08’ X ‘P79-101’ F₁ generation and progeny thereof were screened with the SSR markers for resistance to X. fastidiosa under greenhouse conditions. A highly resistant selection from the ‘F8909-08’ X ‘P79-101’ cross, ‘00504-20’, was crossed to another V. vinifera table grape from a grape breeding program, ‘B52-89’, to create ‘A81-138’, which was also selected for its very high resistance to PD. ‘A81-138’ was then used to cross to V. vinifera wine grapes for several generations of modified backcrossing to obtain the candidate selection ‘09338-016’, which was later named as ‘Caminante Blanc’. These backcrosses were modified because of the high heterozygosity and recessive load found in grapes. Hence, to avoid exposure of deleterious recessive alleles, each generation of backcrossing was to a different and unrelated high quality V. vinifera cultivar.

Accordingly, the parentage of ‘Caminante Blanc’ is ‘07371-20’ (‘F2-35’ (‘Cabernet Sauvignon’ X ‘Carignane’) X ‘U0502-026’ (‘A81-138’ X ‘Chardonnay’)) X ‘Cabernet Sauvignon’ to produce ‘09338-016’. ‘Caminante Blanc’ was particularly selected for its high resistance to Pierce's disease, as well as the quality of its fruit and wines produced therefrom. None of the parents across the multiple backcross generations are patented. ‘09338-016’ has deeply lobed leaves with large irregular teeth on the leaf margin. ‘Cabernet Sauvignon’ is not only very susceptible to X. fastidiosa it has deeply lobed leaves, has lobes with small sinuses in them and has relatively short teeth on the leaf margin. ‘Caminante Blanc’ can be distinguished from its female parent ‘07371-20’ in that ‘Caminante Blanc’ has perfect flowers whereas ‘07371-20’ has pistillate flowers.

BRIEF DESCRIPTION OF THE DRAWINGS

This new grapevine plant variety is illustrated by the accompanying photographs. The colors shown are as true as can be reasonably obtained by conventional photographic procedures. The photographs are of plants that are five to seven years old. Colors referred to are in reference to The Royal Horticultural Society Colour Charts Edition V.

FIG. 1 shows simple sequence repeat (SSW) marker data establishing a DNA fingerprint for ‘Caminante Blanc’ with nine pure Vitis vinifera cultivars for comparison. Alleles for marker-assisted selection of the Xylella fastidiosa locus (PdRl) are shown in red.

FIG. 2 illustrates the upper surface of a leaf of grapevine plant variety ‘Caminante Blanc’.

FIG. 3 illustrates the lower surface of a leaf of grapevine plant variety ‘Caminante Blanc’.

FIG. 4 illustrates a section of a shoot tip of grapevine plant variety ‘Caminante Blanc’.

FIG. 5 illustrates a plant of grapevine plant variety ‘Caminante Blanc’ bearing clusters of berries.

FIG. 6 illustrates a cluster of grapes of grapevine plant variety ‘Caminante Blanc’.

DETAILED BOTANICAL DESCRIPTION

The following is a detailed description of the new grapevine plant variety designated as ‘Caminante Blanc’, including the key differentiating characteristics of this variety and comparisons of characteristics of ‘Caminante Blanc’ to other grapevine varieties. Unless otherwise indicated, evaluation data were taken from five- to seven-year-old plants, grown in Davis, Calif.

-   Classification:     -   -   Family.—Vitaceae.         -   Botanical name.—Vitis vinifera L.         -   Common name.—Grapevine.         -   Variety name.—‘Caminante Blanc’. -   Parentage:     -   -   Female parent.—‘07371-20’ (unpatented).         -   Male parent.—‘Cabernet Sauvignon’ (unpatented) Note that             ‘Cabernet Sauvignon’ is a hermaphroditic cultivar and thus             can be used as a maternal or paternal parent. -   Plant:     -   -   Berries.—Small, golden-green, spherical, with thin whitish             bloom.         -   Clusters.—Small to medium, compact, short conical to             cylindrical often winged.         -   Leaves.—Five-lobed, round in outline, over lapping lateral             sinuses, urn-shaped petiolar sinus with naked veins,             distinctive large sharp teeth on leaf margin, lobes have             extra sinus to make them five- to nine-lobed, red-purple             petiole, glabrous leaves.         -   Shoot tips.—Red-bronze, with sparse tomentum.         -   Production.—Blooms relatively late, ripens mid-season,             medium productivity         -   Method of propagation.—Vegetative propagation via woody or             herbaceous cuttings, or budding and grafting to rootstock.             ‘Caminante Blanc’ has been asexually reproduced in Davis,             Calif. Any rootstock can be used with the variety. Most             often it will be grown on rootstocks that resist grape             phylloxera and or nematodes. In testing, selections were             evaluated grafted on ‘1103P’ rootstock which is not             patented. It was chosen for ease of propagation and because             it is widely used in CA. The variety has been grafted on             many other rootstocks for testing in field trials as well.

‘Caminante Blanc’ has the highest form of resistance to X. fastidiosa coupled with the highest wine quality of any PD resistant wine grape yet produced. ‘Caminante Blanc’ is selected for very high resistance, not the more commonly found tolerance, to prevent the production of host plants capable of further spreading PD to surrounding vineyards.

‘Caminante Blanc’ has a very strong PD resistance and the highest wine quality of any currently used PD resistant wine grape. PD is one of the few diseases that kill susceptible grapevines. Two most popular PD resistant wine grape varieties, ‘Blanc du Bois’ and ‘Lenoir’ (‘Lenoir’ is also known as ‘Black Spanish’ or ‘Jacquez’), were used as controls or standards in all testing so that the wine quality and resistance of the candidate variety could be compared to available PD resistant varieties used across the southern United States. It is noted that ‘Blanc du Bois’ and ‘Lenoir’ have relatively poor wine quality and are tolerant, not resistant, to PD. Neither ‘Blanc du Bois’ nor ‘Lenoir’ are patented.

‘Caminante Blanc’ has far better PD resistance and wine quality when compared with ‘Blanc du Bois’ and ‘Lenoir’. In other words, ‘Caminante Blanc’ combines very strong resistance to X. fastidiosa with the wine quality of internationally acclaimed wine grape cultivars. ‘Caminante Blanc’ was selected as a variety that exhibits high resistance to X. fastidiosa and V. vinifera-like wine quality. The data presented below are intended to further characterize ‘Caminante Blanc’. The appearance of ‘Caminante Blanc’ is illustrated in FIGS. 2-5, and further characteristics of ‘Caminante Blanc’ are shown in FIG. 1 and Tables 1-5.

FIG. 1 presents the DNA fingerprinting profile for ‘Caminante Blanc’ and nine pure Vitis vinifera cultivars for comparison with the standard set of internationally agreed-upon genetic markers. This SSR fingerprinting profile can be used for DNA-based identification.

Table 1 presents typical phenological data for ‘Caminante Blanc’ grown in the UC Davis vineyards. These data are for 2016, but the ranking of the selections in regard to an early cultivar (‘Pinot Noir’) and a late cultivar (‘Cabernet Sauvignon’) have been typical over years. In general, ‘Caminante Blanc’ is phenologically mid-season. Based upon the percentage of V. vinifera in the present variety and the data regarding its parents, the variety is expected to grow in USDA Hardiness Zone 6-7. It is not expected to be drought tolerant

TABLE 1 Average phenological states for ‘Caminante Blanc’. ‘Cabernet Sauvignon’ (late) and ‘Pinot noir’ (early) are included as comparisons. All data were taken from vineyards. 50% Cultivar Budbreak 50% bloom veraison 24 °Brix ‘Caminante Blanc’ 3/17 5/6 7/20 8/17 ‘Cabernet Sauvignon’ 3/24 5/7 7/21 8/30 ‘Pinot Noir’ 3/10  4/30 7/9  8/9 

Table 2 presents the average cluster and berry data for ‘Caminante Blanc’, and averaged over multiple years.

TABLE 2 Average cluster and berry sizes of ‘Caminante Blanc’ and its comparison varieties. Data are averages over multiple years. Number Avg. t-test t-test of Cluster Cluster Avg. Berry Berry Genotype Years Wt. (g) Wt. Wt. (g) Wt. Clusters ‘Caminante 5 290 ab 1.2 c Compact Blanc’ ‘Blanc du Bois’ 6 148 d 1.5 a Well-filled ‘Cabernet 6 132 d 1.2 c Loose to Sauvignon’ well-filled ‘Chardonnay’ 6 196 cd 1.5 ab Well-filled to compact ‘Lenoir’ 6 157 d 1.3 bc Loose

Table 3 presents the average yield per vine data taken over 2016 to 2018.

TABLE 3 Average production data for ‘Caminante Blanc’ and its comparison varieties. Data are averages from three years (2016 to 2018). Avg. Yield/ Std. Dev. Number Genotype Vine (kg) (kg) t-test of Years ‘Caminante Blanc’  7.3 0.9 a 3 ‘Blanc du Bois’ 12.7 1.8 a 3 ‘Cabernet Sauvignon’ 10.9 1.8 a 3 ‘Chardonnay’ 10.9 3.2 a 3 ‘Lenoir’ 20.0 6.8 b 3

Mean berry juice data were also taken and Table 4 presents this data over a five-year period between 2014 and 2018. These values are consistent with cultivars that produce high quality wines.

TABLE 4 Average juice data for ‘Caminante Blanc’ and its comparison varieties. Data are averages from five years (2014 to 2018). Avg. ti- Avg. L- t-test t-test tratable t-test malic t-test Avg. Avg. Avg. Avg. acidity Avg. acid Avg. Genotype °Brix °Brix pH pH (g/L) TA (g/L) MA ‘Caminante 22.2 de 3.55 bc 5.8 cd 1.9 bcd Blanc’ ‘Blanc du 23.5 c 3.58 bc 5.2 de 2.3 bcd Bois’ ‘Cabernet 25.8 b 3.74 abc 5.2 de 1.9 bcd Sauvignon’ ‘Chardonnay’ 23.3 cd 3.68 bc 5.9 cd 2.4 bc ‘Lenoir’ 21.3 e 3.96 a 9.1 a 4.5 a

Xylella fastidiosa susceptibility data are presented in Table 5, which presents the levels of X. fastidiosa in relationship to tolerant (‘Blanc du Bois’ and to a lesser extent, ‘Lenoir’) and susceptible (‘Chardonnay’ and ‘Cabernet Sauvignon’) cultivars. These are also mean data from repeated testing over seasons and greenhouses. Because of the high variation in greenhouse conditions, at least four standards (bio-controls) were always used: ‘b43-17’, ‘Blanc du Bois’, ‘Lenoir’, and ‘Chardonnay’ (and occasionally other V. vinifera cultivars), which allows the data to be compared across greenhouses, tests and seasons. None of these varieties are patented. These varieties tend to be very consistent in the amounts of bacteria they support as well as the severity of their disease expression. The cut-off between resistant and susceptible is usually between 75,000 and 250,000 colony forming units per milliliter (cfu/ml).

TABLE 5 Xylella fastidiosa concentrations based on ELISA readings and converted to colony forming units (cfu/ml). Vitis arizonica ‘b43-17’ is the source of resistance in the breeding program. Geometric Number Mean Least Sq. Std. of Times Cultivar cfu/ml t-test Mean Error Tested ‘b43-17’  12423 a  9.4 0.2 11 ‘Caminante Blanc’  126965 b 11.8 0.4 4 ‘Blanc du Bois’  859096 c 13.7 0.2 11 ‘Lenoir’ 2421748 d 14.7 0.6 2 ‘Chardonnay’ 5197228 d 15.5 0.2 11 ‘Cabernet Sauvignon’ 6582993 d 15.7 0.8 1

TABLE 6 shows phenotype of ‘Caminante Blanc’. The variety has normal hermaphroditic flowers and typical floral development as is found in commercial V. vinifera wine grapes. ‘Caminante Blanc’ Berry size (L, W) 1.3 × 1.4 cm Berry weight, shape 0.8 g/round Seed number, length and width 2 typical for V. vinifera wine grapes, but not measured Cluster #, L, W, 4.0 × 7.0 cm, shape, compactness, 2 short compact clusters/shoot narrow conical, winged to double Yield kg 11.5 Pruning weights 1.55 kg Trunk width at 30 cm 3.0 cm Trunk color and Rough shaggy texture bark 178D Woody shoots 0.8 cm/6.6 cm diameter above cluster/ and internode length Woody shoot texture First year bark and color adheres but peels in strips in second year 164B Active shoot color, 144C internode color above 145A the cluster zone/ 0.8/6.6 cm cluster zone shoot diameter/internode length (shoots same size as woody canes in the cluster zone) Tendril length, 15.0 diameter 0.2 Tendril color, N144D Opposite leaves and alternating 2 nodes skip 2 nodes skip Seed color 165B Cluster size L, W 4.0 × 7.0 cm #Berries/cluster 332 Berry color skin and 145A waxy bloom 190D Berry flesh color 145A Leaves L, W 19.0 × 19.0 cm Leaf arrangement, Alternate, shape, and color palmate with 5 Top/Bottom lobes 141A/144B Petiole L, diameter, 10.7 texture 0.4 smooth Petiole color 71A Shoot tip color (first 79A/143A opened leaf) Budbreak Mar. 17 Bloom date May 12 Harvest date Aug. 18 Peduncle L, diam., 1.0 color, texture 0.5 N144B Smooth

Flower Descriptions

The floral buds and flower clusters are formed with in the latent (dormant) bud in the year before flowering. As the pre-formed nodes on the compressed stems within the latent bud expand and the flower clusters begin developing and the individual flowers on the panicle begin forming. They are very small 2-4 mm and closer to 2 mm with wine grapes.

Berry Descriptions

The variety is not a “slip-skin” type grape. They have skin that adheres to the flesh tightly. They are not firm at ripeness and are soft compared to modern era table grapes at harvest. The pedicels have normal attachment to the berries and are not distinguishable from other V. vinifera wine grapes in this or other morphological features, nor in juice and wine analysis.

Fruit and Juice Parameters

YAN is yeast assimilable nitrogen and helps predict fermentation success. The white grapes have no tannin or anthocyanin values. Seed color is rated as green to brown for mature seeds.

Leaf Descriptions

Rounded leaves with lateral lobes with deep sinuses, and sinuses cutting into the lateral lobes, lyre-U shaped petiolar sinus, large irregular teeth, light tomentum on the adaxial leaf surface, red (71A) petioles with color that diffuses into the main veins

Berry Descriptions

The variety is not a “slip-skin” type grape. They have skin that adheres to the flesh tightly. They are not firm at ripeness and are soft compared to modern era table grapes at harvest. The pedicels have normal attachment to the berries and are not distinguishable from other V. vinifera wine grapes in this or other morphological features, nor in juice and wine analysis.

Fruit and Juice Parameters for the 5 Releases

YAN is yeast assimilable nitrogen and helps predict fermentation success. The white grapes have no tannin or anthocyanin values. Seed color is rated as green to brown for mature seeds.

TABLE 7 presents the wine characteristics of ‘Caminante Blanc’ TA L-malic Potassium YAN (mg/L, °Brix (g/L) pH acid (g/L) (mg/L ) as N) ‘Caminante 21.3 5.7 3.50 1.3 1660 226 Blanc’

Table 8 presents the juice, fruit and seed phenotype of ‘Caminante Blanc’ Juice Juice Hue Intensity Juice Flavor Skin Flavor ‘Caminante green Lt light green apple grass, veg, Blanc’ astringent Skin Tannin Seed Color Seed Tannin (1 = low, (1 = gr, (1 = high, 4 = high) 4 = br) Seed Flavor 4 = low) ‘Caminante 3 4 spicy, hot, 2 Blanc’ sl bitter

‘Caminante Blanc’ has excellent PD resistance. However, itis highly susceptible to a wide range of pests and diseases in a manner similar to other V. vinifera cultivars, and thus it must be treated as a pure V. vinifera cultivar are treated in terms of susceptibility to fungal diseases and pests. ‘Caminante Blanc’ has no known tolerance to adverse weather. 

What is claimed is:
 1. A new and distinct variety of grapevine plant designated ‘Caminante Blanc’ as shown and described herein. 